Apparatus for obtaining hydrogen peroxide by distillation



J. MULLER 1,924,954 -APPARATUS FOR OBTAINING HYDROGEN PEROXIDB BYDISTILLATION Aug; 29, 1933.

Filed Dec. 19, 1929 eECOI/EEY Patented Aug. 29, 1933 APPARATUS FOROBTAINING HYDROGEN PEBOXIDE BY DISTILLATION.

Josef Miiller, Wcissenstein ob der Drau, Austria Application December19, 1929, Serial No. 415,368, and in Germany January 3, 1929 8 Claims.(01. 20252) The invention relates to the production of hydrogen peroxidefrom solutions containing or yielding the same, such as solutions ofpersulphuric acid or solutions of persulphates.

It is already known to submit such solutions, to distillation whileflowing in a thin film of large area which is heated to effect rapidevaporation. A process of this kind is described in the patent toLowenstein No. 1,013,791 which according to the example shown in thisspecification is carried out in such a manner, that the solution to betreated is admitted at the top of a vertical externally heateddistilling tube so as to run downwards over the interior surface of thewall of the tube, while the hydrogen peroxide vapors distilled off aredischarged at the upper end of the tube. Consequently the liquid and thehydrogen peroxide vapors are moving in countercurrent. 1

For the construction of the distilling tubes ceramic material was almostexclusively at the disposal of the practical work, in spite of manyattempts for replacing this fragile material, the heat conductivity ofwhich is very low, by a metallic material which would be more fitted'forthe purpose. On account of the high costs of precious metals theendeavours were especially directed towards finding out ordinarymetallic materials sufiiciently resistant to the several reactioncomponents.

In the patent to Levin and Molin No. 1,323,075

it has been proposed to render possible the use.

of lead for the construction of such heated distilling tubes by aspecial way of carrying out the distilling process which was based onthe assumption that any chemical action between the heated walls of thedistilling tube and the hydrogen peroxide vapors could be avoided, ifthe vapors are removed and condensed as promptly as possible aftergeneration. For this purpose a thin walled lead tube has been used toensure a rapid transfer of heat, in which tube the persulphuric liquidto be treated is introduced at the top, while the peroxide vaporsdistilled off pass upwardly in counter-current to the downward streamingliquid.

Later on it has been proposed to use tantalum for the purpose inquestion. On the other hand also the use of chromium steels (chromiumnickel alloys) has been suggested. But there exists up to now nopossibility of making distilling tubes of tantalum at fairly reasonablecosts, and also the use of chromium steels has not been success ful inpractice.

I have now found that tubes of relatively great length can be employedfor carrying out distillation processes of this kind without, as mighthave been feared, the hydrogen peroxide becoming.- decomposed to anydetrimental extent, even if the tubes of such lengthare made of lead orlike 0 ordinary metal. Thus for instance a length of more than 10 metersmay be chosen, advantageously one more than 30 meters. Excellent resultshave been obtained by using tubes having a length of 50 to 75 meters. 55Lead decomposes persulphuric liquid and is attacked by persulphuricsolutions which on heating yield hydrogen peroxide and sulphuric acid,permonosulphuric acid being produced as an intermediate product; butthis is only the case on the condition that hydrogen peroxide is alreadycontained in the heated persulphuric liquid. On the other hand lead hasbeen found to be perfectly inert (even when the solutions are heated) topersulphuric acid and permonosulphuric acid solutions free of hydrogenperoxide, consequently also to the residual liquor which is produced inthe preparation of hydrogen peroxide by distillation of persulphuricsolutions, provided said residual liquor is free of hydrogen peroxide.

Now in the distillation of the persulphuric liquid prepared for thepurpose of recovering hydrogen peroxide therefrom first of all the persulphuric acid is transformed into monopersulphuric acid without anyhydrogen peroxide being generated meanwhile. Consequently lead isperfectly inert to the acids in question in the first section of thedistilling tube. Only when nearly the whole persulphuric acid has beenconverted into monopersulphuric acid, the generation of hydrogenperoxide will set in. In this moment, however, there is with distillingtubes of suitable dimensions already such a high speed of the vapoursattained (e. g. 100 meter per second increasing up to 300 m/sec.) that amutual chemical action between the wall of the lead tube and thehydrogen peroxide vapors is avoided, the more so as the wall is alsoprotected by an outermost thin layer of the persulphuric liquidstreaming along the heated wall, which outermost layer forms a coveringfilm of mother liquid perfectly freed from hydrogen peroxide. v

The velocity of flow is inversely proportionate to the cross-section ofthe distilling tube, that is 'to say, it diminishes in direct proportionwith the increase of the sectional area of the distilling tube. On theother hand the speed increases proportionally with the throughput(amount of charge per unit of time). Consequently the lower streamingvelocity in tubes having a larger sectional area maybe balanced byincreasing the throughput. The throughput on its part is'limited by thelength of the tube, since in tubes being not long enough the hydrogenperoxide vapors formed'by hydrolysis are not completely driven out ofthe liquid under treatment. I

As is seen therefrom, the speed can be adjusted at will within certainlimits by the choice of an appropriate relation between the length andthe sectional area of the tube, so that any decomposition of thehydrogen peroxide can be avoided even ifdistilling tubes of considerablelength are employed.

Moreover I have ioundthat advantageously by distillation of solutionscapable oi liberating spiral tubes can be used as distillationapparatus, as they can be disposed in a small space and be uniformlyheated in a simple manner.

The tubes'may for instance be made oi. metallic material highlyresistant to acids and to the action of active oxygen (e. g. gold orplatinum) or inside plated therewith. But most advantageously lead orlead alloys are used for this purpose (in the one or the other of theseways).

It has for instance been found advantageous, if for a length of the pipeamounting to 60 meters an internal diameter of 75 millimeters is chosen.

In the following an example of carrying the invention into practice isgiven, reference being made tothe annexed drawing which shows a partlysectional elevation oi! a distillation apparatus.

Within a steam jacket 1 a distilling tube wound in the form of a spiralor, as shown, in that of a helical coil 2 is enclosed, the two'ends'ofwhich pass through stufiing boxes 3 providedon the jacket. This coilconsists for instance of a thick walled lead tube 75 millimeters wideand 60 meters in length, which is wound into a coil about 10 to 25 turnsor windings. Steam can be admitted through the pipe 4 and the waterresulting from condensation drawn off through the pipe 4'. The acid tobe treated is supplied at the top of the coil to flow downwards.

About 200 to 250 liters per hour of sulphuric acid containingpersulphuric acid (25%H2S2Oa) are passed through this coil in thedownward direction. The vacuum amounts to about 650 to 700 millimeters.The hydrogen peroxide given off may be recovered in suitable condensers,if necessary, by means of fractional condensation.

By the invention the obtaining 01' high yields of hydrogen peroxide fromsolutions of persulphuric acid or the like by means of a very simpleapparatus is rendered possible, which apparatus can very easily beoperated. The consumption of steam which in the commercial production ofhydrogen peroxide by distillation is of great importance, is relativelyvery small;

1. A process for obtaining hydrogen peroxide by distillation ofsolutions capable of liberating it, which consists in passing thesolution and the liberatedhydrogen peroxide vapors in the same directionthrough a heated ascending distilling tube of more than ten meters inlength, the liquid to be distilled being admitted at the, top of thesaid distilling tube to flow downwards.

2. A processgfpr obtaining hydrogen peroxide it, which consists inpassing the solution and the liberated hydrogen peroxide vapors in thesame direction through an externally heated ascending distilling tubeoi'more than ten meters in length, the liquid to be distilled beingadmitted at the top of the said distilling tube to flow downwards.

3. A process for obtaining hydrogen peroxide by distillation ofsolutions capable of liberating it, which 'consists in passing thesolution and the liberated hydrogen peroxide vapors in the samedirection through an" externally heated distilling tube formed into acoil of a length of more than ten meters, the liquid to be distilledbeing admitted at the top of the said coil to flow downwards.

4. A process for obtaining hydrogen peroxide by. distillationofsolutions capable of liberating it, which consists in passing thesolution and the liberated hydrogen peroxide vapors in the samedirection through an externally heated distilling tube formed into ahelical coil of more than ten meters in length, the liquid to bedistilled being admittedat the top of the said distilling tube to iiowdownwards.

5. A process for obtaining hydrogeh peroxide '.by 'distillation ofsolutions capableof liberating it, which consists in passing, thesolution and the liberated hydrogen peroxide vapors in the samedirection through an externally heated ascending distilling tube ofmore-than ten meters in length which offers to the solution an internalby distillation of solutions capable of liberating it, which consists inpassing the scfiiiti'on and the liberated hydrogen peroxide vapors inthe same direction through an externally heated ascending distillingtube of more than ten meters in length, this tube being made from lead,the liquid to be distilled being admitted at the top of said distillingtube to flow downwards. 7. A process for obtaining hydrogen peroxide bydistillation of solutions capable of liberating the it, which consistsin passing the solution and the it, which consists in passing thesolution and the liberated hydrogen peroxide vapors in the samedirection through a heated coiled distilling tube of more than tenmeters in length while lowering the 'iistillationtemperature by applyina vacuum,

the liquid to be distilled being admitted atTt e 65 of the saiddistilling tube to flow downwards.

' JOSEF MULLER.

